feat: 增加 SafeW 已监控群列表接口

通过 getUpdates 将群写入 Redis，供创建/编辑渠道时选择 chat_id，避免前端重复传递 token。

internal/safew/watcher_test.go

@@ -0,0 +1,76 @@
+package safew
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+
+	"aiaa-notification-service/internal/adapter"
+)
+
+func TestRefreshMergesAndAdvancesOffset(t *testing.T) {
+	st := NewMemStore()
+	poll := func(token string, offset int64, timeout int) ([]adapter.SafewChat, int64, error) {
+		if timeout != 0 {
+			t.Fatalf("timeout=%d", timeout)
+		}
+		if offset != 0 {
+			t.Fatalf("offset=%d", offset)
+		}
+		return []adapter.SafewChat{{ID: "10000778141", Type: "group", Title: "测试AI"}}, 11, nil
+	}
+	w := NewWatcher(st, poll)
+	ctx := context.Background()
+	if err := w.Refresh(ctx, "tok"); err != nil {
+		t.Fatal(err)
+	}
+	list, err := w.List(ctx, "tok", "测试")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(list) != 1 || list[0].ID != "10000778141" {
+		t.Fatalf("%#v", list)
+	}
+	off, _ := st.GetSafewOffset(ctx, "tok")
+	if off != 11 {
+		t.Fatalf("offset=%d", off)
+	}
+}
+
+func TestRefreshAuthError(t *testing.T) {
+	st := NewMemStore()
+	w := NewWatcher(st, func(string, int64, int) ([]adapter.SafewChat, int64, error) {
+		return nil, 0, &adapter.SafewAuthError{Description: "BOT_TOKEN_INVALID"}
+	})
+	err := w.Refresh(context.Background(), "bad")
+	if err == nil {
+		t.Fatal("expected auth error")
+	}
+	if _, ok := err.(*adapter.SafewAuthError); !ok {
+		t.Fatalf("%T", err)
+	}
+}
+
+func TestEnsurePollsInBackground(t *testing.T) {
+	st := NewMemStore()
+	got := make(chan int, 1)
+	w := NewWatcher(st, func(token string, offset int64, timeout int) ([]adapter.SafewChat, int64, error) {
+		if timeout != 30 {
+			return nil, offset, errors.New("not background")
+		}
+		select {
+		case got <- timeout:
+		default:
+		}
+		return []adapter.SafewChat{{ID: "1", Type: "group", Title: "g"}}, offset + 1, nil
+	})
+	w.bgIdle = 10 * time.Millisecond
+	w.Ensure("tok")
+	select {
+	case <-got:
+	case <-time.After(2 * time.Second):
+		t.Fatal("background poll not called")
+	}
+	w.Stop()
+}